भगवत्युत्तमश्लोके जघ्नुस्ते पापनिश्चया: ॥ ११ ॥
jaghnus te pāpa-niścayāḥ
dṛṣṭvā — by seeing; agni-āgāre — at the place where the fire sacrifice is performed; āsīnam — sitting; āveśita — completely absorbed; dhiyam — by intelligence; munim — the great sage Jamadagni; bhagavati — unto the Supreme Personality of Godhead; uttama-śloke — who is praised by the best of selected prayers; jaghnuḥ — killed; te — the sons of Kārtavīryārjuna; pāpa-niścayāḥ — determined to commit a greatly sinful act, or the personified sins.
The sons of Kārtavīryārjuna were determined to commit sinful deeds. Therefore when they saw Jamadagni sitting by the side of the fire to perform yajña and meditating upon the Supreme Personality of Godhead, who is praised by the best of selected prayers, they took the opportunity to kill him.